1. Field of the Invention
The present invention relates generally to the field of user interactive media interfaces and, more particularly, to a wireless pointing device for cursor control in interactive television and computer presentation graphics.
2. Description of the Prior Art
A generally established method to provide human interaction with a system controlled by a computer is to provide the user with a graphical display of choices and a pointing device, such as a cursor controlled by a mouse. The pointing device is used to manipulate the position of a cursor on the computer display or television (TV) screen to designate to the computer some desired action. The pointing device is usually provided with a computer-sensed button or switch, which can be pressed to cause the action to occur.
There is a need for a selection device with the functional capability of a mouse, specifically the ability to (1) designate a displayed option for action by moving a cursor, and (2) initiate the action by pressing a button. For consumer applications, it is important that the device be intuitive to use.
In the field of interactive television, the setting may be the home television room and the user may be any untrained member of the household. It is common for the user to be seated six feet or more from the television set, and thus out of reach of any controls built into or connected to the television. In the field of computer presentation graphics, the setting may be a lecture room, classroom, or unprepared demonstration area, and those present, who may have minimal training, may be standing or walking freely about the room.
The majority of pointing devices were developed for desktop use in conventional computing environments, and are poorly suited for the above applications. For example, a mouse, joystick or trackball is normally wired to the computer. The mouse requires a smooth, flat surface on which to roll, while the joystick or trackball must be fixed in a stable position for smooth operation. These devices also require some degree of fine muscle control and are difficult to use while standing or seated away from a desk. Furthermore, they are not intuitive devices, so that untrained users may find it difficult to grasp the relationship between the cursor position and the hand or finger motions required to move it.
An alternative device which eliminates the wire is a joystick or trackball built into a handheld device. The motion of the ball or stick may be sent to the computer via an infrared (IR) or radio frequency (RF) communication link. Such devices suffer from the other problems mentioned above and may require two handed operation, a further disadvantage.
Yet another alternative is a wireless hand held device equipped with an array of pushbuttons or a multi-element rocker switch. These do not require a stable surface, but they do require the user to remove his eyes from the screen to locate buttons. They are even less intuitive than the other devices, as the user is required to grasp the relationship between an arbitrary button and text or images displayed on the screen.
U.S. Pat. No. 4,565,999 to King et al. describes a xe2x80x9clight pencilxe2x80x9d. This is head mounted and used to steer a cursor by head motion. Four infrared light emitting diodes (IRLEDs) are used in the light pencil, with a single detector at the screen. The IRLEDs are aimed somewhat off-axis in orthogonal directions and pulsed sequentially, allowing the received signal from each to be separately measured. The four values are used to compute an aiming direction. The light pencil, as described by King et al., lacks push-button function (head gestures are used) and has rather crude digital filtering to reduce cursor jitter caused by muscular tremors. The intent is to enable a person to position a cursor by turning the head in the desired direction. While such a device could also be held and aimed manually, the preferred embodiment as described in King et al. uses an awkward head motion (an abrupt nod) to initiate action after the cursor is positioned. Other shortcomings related to the implementation will be discussed below.
It is therefore an object of the present invention to provide a wireless device to manually position a cursor on a display device by an intuitive direct pointing action.
It is further an object of the invention to provide the pushbutton function of a standard computer pointing device and in such a way that the anticipatory and final motions involved in pressing the button do not affect the cursor position.
It is also an object of the invention to provide a mechanism for the transmission of binary codes to a remote television at negligible additional cost.
According to the invention, there is provided an infrared controller for an interactive device, such as a television or video cassette recorder (VCR). The device allows a cursor to be positioned merely by aiming the controller. It includes means for push-button activation and optionally provides for the transmission of the usual controller codes.
The invention is a combination of the aiming function of a light pencil and the code-transmitting function of an infrared television or VCR controller, in which the internal mechanism of the controller is shared between the two functions. The innovative combination provides an intuitive mechanism to position a cursor by rotating the controller in the desired direction. It also provides for push-button activation of the action designated by the cursor and optionally provides for transmitting television or other control codes.
The invention makes use of the principles of a light pencil, with improvements in the data processing to provide better performance, the addition of a new function in the form of push-button actuation, and further new functions allowing the transmission of standard control codes. In addition, a diffusion filter is added to smooth out irregularities in the LED output variation with angle. Such variations, if uncorrected, were found to introduce irregular variation in cursor motion with pointing direction.
The invention makes use of the optical technology of King et al. In a conventional infrared (IR) controller, a single infrared light emitting diode (IRLED) is used to transmit coded information in the form of a timed series of modulated pulses. According to the present invention, three or more IRLEDs are mounted in the hand-held device, with their optical axes fanned out from the main axis of the device. For example, one IRLED may point down and to the left, the second may point down and to the right, and the third may point forward and up. Many other arrangements of IRLEDs are possible. The hand held device includes at least one pushbutton, referred to as the action button, but may include others. The action button is used to initiate an action responsive to the position of the cursor.
An infrared detector is located in the general vicinity of the television or computer display. The IRLEDs are pulsed sequentially and the amplitudes of the light pulses reaching the detector are measured by a computer-controlled circuit connected to the detector. The light from an IRLED decreases progressively with an increase of the angle from its optical axis. Therefore, the relative amplitudes of the pulses will vary systematically with overall orientation of the device. The pointing direction is determined from the measured amplitudes, and used to position the cursor.
Coded information is sent by adding additional pulses to the pulse train. These pulses may be applied to all three IRLEDs to ensure reliable detection, or an additional IRLED may be used for this purpose. Any binary code may be sent in this way. One such code is used to indicate that the action button has been pressed. Additional buttons may be used to send other codes, enabling the device to emulate a two or three button pointing device and/or provide television-related control functions.